Question

If p(x) is a quadratic function and p(-1) = p(7) = 2,

which of the following could be the coordinates of
the vertex of the parabola formed when y = p(x) is
graphed in the xy-plane?
PLEASE EXPLAIN- I really don’t know:,)

(0,8)
(4,3)
(6,7)
(3,9)

Answer 1

3,9

Explanation:

hint: quadratic function

the form can be x² or x²+b or x²+bx+c

when p(-1)= 2 it means if we take x-axis = -1 the result (y-axis) will be 2. Same thing happen if we take x = 7

the vertex will always in the middle. So the middle of x = -1 and x = 7 is 3

-1, 0, 1, 2, 3, 4, 5, 6, 7

the vertex will occured when x = 3

the only answer with x = 3 is the fourth one (3,9)